/Engine/Source/Runtime/Engine/Classes/Kismet/GameplayStatics.h
Linearly interpolates the attenuation distance scale value from it's current attenuation distance override value (1.0f it not overridden) to its new attenuation distance override, over the given amount of time
static void SetSoundClassDistanceScale ( const [UObject](API\Runtime\CoreUObject\UObject\UObject) * WorldContextObject, [USoundClass](API\Runtime\Engine\Sound\USoundClass) * SoundClass, float DistanceAttenuationScale, float TimeSec )